Ischemia identification, quantification and partial localization MCG

Abstract

A magnetic dipole model based on MCG data of the heart is used to localize cardiac tissue afflicted with ischemia. The direction of displacement of the dipole during the ST segment, superimposed on the heart's general outline, indicates a rough location of the ischemic cardiac tissue. Furthermore, the extent of ischemia is quantified based upon the how much displacement occurs in the ST segment. For example, if significant dipole's displacement occurs in the first quarter of the ST segment, then it is identified as a first-degree ischemia. Similarly, if displacement occurs in ½, ¾, or 1 full ST segment, then the level of ischemia is identified as second degree, third degree, or fourth degree ischemia (fourth degree being the worst kind of ischemia where the dipole's position is dynamic all through the ST segment).

1 . A system for identifying and localizing ischemic cardiac tissue comprising: 
 a system measuring magnetic cardiac cycle data and modeling an effective dipole as a source of said measured magnetic data at a proximate point on an ST segment of said measured magnetic data;    an ischemia localizer calculating and visualizing spatial positions associated with said modeled dipole over a remainder of said ST segment, and    an ischemia identifier identifying significant movement and a direction associated with said movement of said dipole over said ST segment, and in case of a moving dipole: 
 said heart identified as having ischemic tissue, and  
 said direction of movement identified as pointing to a general location of said ischemic cardiac tissue.  
   
     
     
         2 . A system for identifying and localizing ischemic cardiac tissue, as per  claim 1 , wherein said system further comprises: 
 an ischemia quantifier identifying a percentage of said ST segment over which said displacement of the effective dipole source occurs and matching said percentage with a predetermined quantification level of ischemia.    
     
     
         3 . A system for identifying and localizing ischemic cardiac tissue, as per  claim 2 , wherein said predetermined quantification levels of ischemia include the following levels: healthy heart without ischemia, light ischemia, severe ischemia, and most severe ischemia.  
     
     
         4 . A system for identifying and localizing ischemic cardiac tissue, as per  claim 3 , wherein said quantification level for most severe ischemia corresponds to the case in which said displacement of said effective dipole does not cease its motion during essentially the whole duration of said ST segment.  
     
     
         5 . A system for identifying and localizing ischemic cardiac tissue, as per  claim 1 , wherein said magnetocardiographic system utilizes SQUID sensors to obtain cardiac data.  
     
     
         6 . A system for identifying and localizing ischemic cardiac tissue, as per  claim 1 , wherein the heart is visualized by known heart visualization techniques such as X-rays, fluoroscopy, MRI and the general outline of the heart is superimposed with the said dipole's succession of spatial positions.  
     
     
         7 . A method for ischemic cardiac tissue identification and localization based upon a magnetic or current dipole model of the heart, said method comprising the steps of: 
 (a) magnetically measuring a cardiac cycle of a heart and modeling said heart as an effective dipole;    (b) identifying an ST segment in said measured cardiac cycle;    (c) identifying a spatial location of said dipole at the beginning of said ST segment;    (d) detecting any significant displacement in the location of said dipole during the remainder of said ST segment;    (e) identifying said significant displacement of said effective dipole with the presence of ischemic tissue in the heart, and    (f) referencing the direction of said significant displacement of said effective dipole with respect to heart's general location and anatomy, and    (g) localizing the general location of said ischemic cardiac tissue as being pointed to by said identified direction of displacement of said effective dipole.    
     
     
         8 . A method for ischemic cardiac tissue identification and quantification based upon an effective magnetic or current dipole model of the heart, as per  claim 7 , wherein said method further comprises the steps of: 
 (a) identifying a percentage of said ST segment over which said dipole's significant displacement occurs, and    (b) matching said percentage with a predetermined quantification level of ischemia.    
     
     
         9 . A method for ischemic cardiac tissue identification and localization based upon a magnetic or current dipole model of the heart, as per  claim 7 , wherein said magnetocardiogram utilizes SQUID sensors to obtain cardiac data.  
     
     
         10 . A method for ischemic cardiac tissue identification and quantification based upon a magnetic or current dipole model of the heart, as per  claim 8 , wherein said magnetocardiogram utilizes SQUID sensors to obtain cardiac data.  
     
     
         11 . A method for ischemic cardiac tissue identification and localization based upon a magnetic or current dipole model of the heart, as per  claim 8 , wherein said method further comprises the step of displaying a graph of said succession of spatial positions of said dipole in the said ST segment, said graph displayed in visual relationship to the general heart's outline, said graph aiding in visually identifying the location of ischemic tissue in the heart.  
     
     
         12 . A method for ischemic cardiac tissue identification and quantification based upon a magnetic or current dipole model of the heart, as per  claim 8 , wherein said method further comprises the step of displaying a graph of said displacement of said dipole versus time during said ST segment, said graph aiding in visually identifying a quantified level of ischemia.  
     
     
         13 . A method for identifying, localizing and quantifying ischemia, said method comprising the steps of: 
 (a) receiving cardiac cycle magnetic data and modeling said heart as a dipole;    (b) identifying an ST segment in said measured cardiac cycle;    (c) identifying said dipole's position at the beginning of said identified ST segment;    (d) determining whether said dipole significantly moves during any part of the ST segment;    (e) identifying the direction of said movement of said dipole's position in reference to the general position and anatomy of the heart;    (f) localizing ischemic cardiac tissue based upon said identified direction of displacement;    (g) dividing the total time duration of said ST segment into four equal duration sub-segments;    (h) identifying significant displacement of said dipole in each of said four subsegments, and    (i) assigning a quantified level of ischemia based on the following rules: 
 if said identified significant displacement occurs in a first of said four segments, then identify said quantified level as first degree ischemia, else  
 if said identified significant displacement occurs in a first two of said sub-segments, then identify said quantified level as second degree ischemia, else  
 if said identified significant displacement occurs in a first three of said sub-segments, then identify said quantified level as third degree ischemia, else  
 if said identified significant displacement occurs in all four of said sub-segments, then identify said quantified level as fourth degree ischemia.  
   
     
     
         14 . A method for identifying, localizing and quantifying ischemia, as per  claim 13 , wherein said method further comprises the step of displaying a graph of dipole's trajectory in three-dimensional space and a graph of dipole's succession of positions in the general direction of its motion as a function of time, said graphs aiding in visually identifying the general location of ischemic tissue and in quantification of the level of ischemia.  
     
     
         15 . A method for identifying, localizing and quantifying ischemia, as per  claim 13 , wherein said cardiac cycle data is received from a magnetocardiogram utilizing SQUID sensors.  
     
     
         16 . An article of manufacture comprising a computer usable medium having computer readable program code embodied therein for localizing ischemic cardiac tissue, said medium further comprising: 
 (a) computer readable program code receiving magnetic cardiac cycle data of a heart and modeling said heart as a dipole;    (b) computer readable program code identifying an ST segment in said measured cardiac cycle;    (c) computer readable program code identifying said dipole's position at the beginning of said ST segment;    (d) computer readable program code detecting any significant displacement in the location of said dipole during the rest of said ST segment;    (e) computer readable program code identifying the direction of said displacement of said dipole with respect to heart's general outline and anatomy, and    (f) computer readable program code localizing ischemic cardiac tissue based upon said identified direction of displacement.    
     
     
         17 . An article of manufacture comprising a computer usable medium having computer readable program code embodied therein for localizing ischemic cardiac tissue, as per  claim 16 , wherein said medium further comprises: 
 (a) computer readable program code identifying a percentage of said ST segment over which said dipole's significant displacement occurs, and    (b) computer readable program code matching said percentage with a predetermined quantified level of ischemia.    
     
     
         18 . A tool for detecting and localizing ischemic cardiac tissue and quantifying level of ischemia in afflicted cardiac tissue, said tool comprising: 
 measuring magnetic cardiac cycle data of a heart and modeling said data based upon a magnetic dipole model of said heart;    isolating an ST segment in said cardiac cycle data;    identifying said dipole's position at a proximate point on said isolated ST segment;    said tool further functioning in any of, or a combination of, the following modes: a detection and localizing mode or quantifying mode, and 
 in a localizing mode, said tool: 
 detecting dipole's displacement during a remainder of said ST segment;  
 identifying direction of said displacement, and  
 localizing ischemic cardiac tissue as heart's region in said identified direction of displacement,  
 
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 in a quantifying mode, said tool: 
 identifying dipole's displacement during said ST segment;  
 dividing said ST segment into two or more sub-segments;  
 identifying number of said sub-segments where said dipole's displacement occurs, and  
 quantifying level of ischemia by matching said identified number of said sub-segments where said displacement occurs with predetermined quantification levels.  
 
   
     
     
         19 . A tool for localizing ischemic cardiac tissue and quantifying level of ischemia in afflicted cardiac tissue, as per  claim 18 , wherein said tool further comprising a display showing a graph of said displacement versus time, said graph aiding in visually identifying quantified level of ischemia.  
     
     
         20 . A tool for localizing ischemic cardiac tissue and quantifying level of ischemia in afflicted cardiac tissue, as per  claim 18 , wherein said predetermined quantification levels of ischemia include the following levels: healthy heart without ischemia, light ischemia, severe ischemia, and most severe ischemia.  
     
     
         21 . A tool for localizing ischemic cardiac tissue and quantifying level of ischemia in afflicted cardiac tissue, as per  claim 20 , wherein said quantification level for most severe ischemia corresponds to a instance in which said displacement of said dipole continuously moves over essentially the entirety of said ST segment.